A suicide car bomber has killed a deputy governor and five other people in eastern Afghanistan, police said.

In an emotional speech, President Hamid Karzai urged Afghans to decry such violence amid concerns that young people will choose to flee their country.

The attack happened as the official was driving towards his office in Ghazni city, said Ghazni province police chief Zarawar Zahid. The bomber rammed into one of the vehicles in the two-car convoy, sparking a large blast.

All of those in the convoy were killed, including Deputy Governor Khazim Allayar, his adult son, his driver and three bodyguards, Mr Zahid said. Twelve people nearby were wounded, he added.

Afghan government officials are prime targets for the Taliban and other insurgent groups which have instituted an assassination campaign against people who work with either the Afghan government or Nato forces.

Mr Allayar had held the post for more than seven years. He survived a bombing attempt in Ghazni city just two months ago.

Mr Karzai called on his fellow Afghans to decry such violence during a speech in the capital about literacy efforts in the country.

"Our sons cannot go to school because of bombs and suicide attacks. Our teachers cannot go to school because of clashes and threats of assassination. Schools are closed," he said.

Mr Karzai said he fears that those among Afghanistan's youth who can flee have no choice but to abandon their country. They go to school abroad and then become estranged from Afghanistan.

"I don't want my son Mirwais to be a foreigner. I want Mirwais to be Afghan," Mr Karzai said, breaking into tears on the podium